Insect & disease management inside green house

Protected cultivation- EC-24
(2+1)
PRESENTED BY:
RAKESH KUMAR PATTNAIK
Asst. Prof. Horticulture
MITS INSTITUTE OF PROFESSIONAL STUDIES
Lecture 16. Insect & disease management inside
green house
Dt.06.07.20

Integrated disease management in greenhouses
Integrated disease management is the practice of using a
range of measures to prevent and manage diseases in crops.
Hazard analysis is used to identify the potential for infection so
that preventative or curative measures can be put in place to
minimise the risk of disease infection and spread. During the
cropping cycle, regular crop monitoring is used to decide if and
what action is needed.
 IPM is fundamentally a subset of the good agricultural practices needed to produce profitable and productive
crops in a sustainable way.

A disease can be controlled by removing the pathogen with
hygiene or a pesticide, changing the environmental conditions to
one that does not favour the pathogen or using of
resistant/tolerant variety so that there is not a suitable host.
Hygiene
 Make sure that any materials, containers, or equipment that you bring into the greenhouse is clean
 Install and maintain a foot bath at every entrance to the greenhouse.
 Make sure every person entering the greenhouse uses the footbath each and every tim
 Another important strategy is to require all workers who smoke to wash their hands thoroughly with
medicated soap before entering the production area.

Control entry
 It is important to understand that pathogens (and pests) are
easily carried on clothing and shoes
 When people are visiting, have them wear disposable
overalls. Avoid visitors.
Start with disease-free plants
 Buying seedlings, inspect them upon delivery.
 If any plants have disease symptoms, tell the delivery person immediately.
 Remove the diseased looking plants and put them in sealed plastic bags and submit them for diagnostic
testing.
 Choose crops and varieties that are resistant to pests and diseases if feasible.
 Many cultivars are resistant or tolerant to several diseases including Powdery Mildew, Downy Mildew
and viruses

Control the growing environment
 Good temperature and humidity management are essential to minimising disease
in greenhouse crops, particularly for Downy and Powdery mildews and Botrytis.
 Guttation is an important way in which pathogens can infect greenhouse crops.
 Condensation on leaves, tissue damage such as pruning and picking wounds,
chilling injury or heat damage predisposes plants to infection.
 Condensation on leaves, tissue damage such as pruning and picking wounds,
chilling injury or heat damage predisposes plants to infection.
 Condensation can also affect fungicide activity by diluting fungicide applications.

Inspect plants regularly
• Walk up and down every row and inspect at least 5% of
all plants in the crop.
• Some diseases will occur in certain locations in a
greenhouse because of localised “microclimates”. For
example, Powdery Mildew usually starts in the shadier
areas.
• Botrytis occurs where moisture sits on plant surfaces.
Waste management
 Remove and destroy crop residues as soon as
possible after pruning and harvest.
 Do not pile plant material near the greenhouse.
 Put pruned material directly into bags or a
rubbish skip bin for disposal – not on the
ground
 Crop debris can be buried if done immediately.

Control insects and weeds
 If feasible, place insect screens over all openings in your
greenhouse.
 Be aware that screens reduce the flow of air and will impact
on the venting capacity of the structure.
 Poor air circulation can result in diseases such as Botrytis
(grey mould), Alternaria (leaf spot) and Pseudoperonospora
(Downy Mildew).
 The use of a double-door entry to the greenhouse, with a
footbath, greatly reduces both pests and diseases getting into
the crop.

Fungicides
 There are two different types of fungicides used to manage
diseases – protectants and eradicants
 Protectants sit on the surface of plants and their mode of action relies on contact with pathogens for
control.
 As new growth needs to be protected, growing plants need on-going protectant spray applications
• Eradicants or curatives are systemic pesticides and are absorbed by plants.
• Their mode of action controls pathogens at sites some distance away from where the chemical
droplets land on the plant.
• These chemicals may move into new growth and therefore do not need to be applied as often as
protectants.

INTEGRATED PEST MANAGEMENT UNDER PROTECTED
ENVIRONMENT: PRINCIPLES AND PRACTICES
 The warm, humid conditions and abundant food under protected conditions provide an excellent, stable
environment for pest development.
 The damage inflicted by arthropod pests on greenhouse crops varies with the pest and season
 Producers of vegetable crops generally can accept a higher level of damage than those of ornamental crops that
are produced for their aesthetic value.
 Integrated pest management (IPM) is a systematic approach to manage pests that combines a variety of
techniques and strategies to either reduce pest populations or lessen their economic impact.
 It is a site-specific strategy for managing pests that relies on correct pest identification and understanding the
pest biology.

Insects and Mite Pests under Protected Environment
 The growing conditions within the protected environment of greenhouse/
polyhouse are highly favourable to arthropod pests.
 In India, about twenty insect and mite species have been recorded to be
associated with the crops under protected environment.
 Some of the important pest groups are aphids (Myzus persicae, Aphis
gossypii), caterpillars (Spodoptera spp., Helicoverpa armigera), leafminer
(Liriomyza trifoli), mites (Tetranychus urticae and Polyphagotarsonemus
latus), thrips (Thrips tabaci and Scritothrips dorsalis) and whiteflies
(Trialeurodes vaporariorum and Bemisia tabaci).

Table 1. Insect-pests Scenario under Protected Environment in India
Group Insect and mite
pests
Host Distribution
Aphids Aphis gossypii Capsicum Punjab, Delhi
Macrosiphoniella
sanborni
Chrysanthemum Karnataka, HP
Macrosiphum luteum Orchid Sikkim
Myzus escalonicus Strawberry New Delhi
Myzus persicae Capsicum, Gerbera, Punjab,
Maharashtra
Toxoptera aurantii Orchid Sikkim
Caterpillars Helicoverpa
armigera
Capsicum, tomato,
carnation
Punjab,
Uttrakhand, H.
P.
Spodoptera litura Rose,
tomato, capsicum,
cucumber
Karnataka,
Punjab, HP
Leaf-miner Liriomyza trifolii Tomato, cucumber,
chrysanthemum,
gerbera, and many
ornamentals
Karnataka, H.P.
Mites Polyphagotarsonemus
latus (yellow mite)
Capsicum Karnataka,
Punjab, Delhi, H.P.
Stenotarsonemus
fragariae
Strawberry New Delhi
Tetranychus cinnabarinus Carnation Maharashtra
Tetranychus
neocalidonicus
Cucumber New Delhi
Tetranychus
urticae (Spider mite)
Tomato, capsicum,
cucumber, carnation,
gerbera
H.P., Maharashtra
Thrips Scritothrips dorsalis Rose Karnataka
Thrips palmi Gerbera Karnataka
Thrips tabaci Gerbera Maharashtra
Whiteflies Bemisia tabaci Gerbera, capsicum Karnataka, Pumjab
Trialeurodes
vaporariorum
Tomato, cucumber,
capsicum, beans,
gerbera, and more
than 30 hosts
H.P.and Nilgiri hills
(TN)

Aphids
Aphids or plant lice are small, soft-bodied, sedentary
insects that form colonies on the leaves and stems of the host
plants. They suck the cell sap from leaf or apical growing
parts and prefer to feed on tender, young growth
Feeding by aphids can cause leaves or stems to curl or
pucker. This leaf distortion often protects the aphids from
contact insecticides. They also secrete honeydew on which
black sooty mold develop in the periods of high atmospheric
relative humidity which interferes with photosynthetic
activity. They also act as vector of many viral diseases.

Caterpillars
Two species of caterpillars are associated with the crops
under protected environment. These are tobacco caterpillar (S.
litura) and tomato fruit-borer (H. armigera).
Tobacco caterpillar:
They are mainly foliage feeders, but occasionally damage fruits.
Eggs are deposited by female moths that have made their way
into the greenhouse and lay eggs in large masses. Heavy
infestations may occur in isolated areas within the greenhouse,
and timely spot treatments can often provide effective control
Thiomethoxam

Tomato fruit-borer: Tomato fruit-borer is one of
the most significant insect-pests of field-grown
crops. They are less common in greenhouses, but
when infestations do occur, they can cause serious
losses. This is because, as their name implies, this
caterpillar feeds directly on the fruit
Tomato fruit borer feed on blooms, as well as
immature and fruits.

Leafminers
Leafminers are larvae of small flies. They damage plants by
feeding between the upper and lower surface of the leaf by forming
mines. The mines increase in width as the larva grows. When fully
grown, the larva emerges from the leaf and fall to the ground to
pupate.
Damage is caused by larvae mining the leaves. If the infestation
is severe, photosynthetic activity is reduced affecting plant vigour.
Because the damaging stages of the insects occur entirely inside the
leaf, control with contact insecticides is ineffective once the damage
appears. Infestations can be avoided through the use of good cultural
practices, hand romoval and disposal of infested leaves and use of
chemical controls when necessary.

Mites
Mites are sap-sucking pests which attack a wide range of greenhouse
plants. Two species, the two-spotted spider mite (T. urticae) and the yellow mite
(P. latus), are known to be persistent problems.
Heavy infestations of the two-spotted spider mite produce fine webbing
which may cover the entire plant. Generally they feed on the undersides of
leaves, giving the upper leaf surface a speckled or mottled appearance. Leaves
of mite-infested plants may turn yellow and dry up, and plants may lose vigour
and die when infestations are severe.
These mites thrive when the temperature is mild with humid environment and
can complete their life cycle in about two weeks. Depending on the type of plant
attacked, they may infest the entire plant or be concentrated around the buds.
Infested leaves become distorted and often curl inward; foliage may become
darker than that of healthy leaves.
Abamectine

Thrips
Thrips infest the leaves, flowers, buds and
young fruits of a crop. They feed by rasping the
plant surface and sucking up the exuding sap.
Heavily infested leaves have a mottled or silvery
appearance.

Whiteflies
• Whiteflies are serious pests in the greenhouse.
• Two species of whiteflies are prevalent under protected environment namely,
greenhouse whitefly (T. vaporariorum) and cotton whitefly (B. tabaci). The former is
prevalent in temperate regions whereas the other is a serious pest in tropical and sub-
tropical parts of the country.
• Whiteflies are small snowy white in colours, about 2 mm in length, flutter from the
undersides of leaves when the plants are disturbed. The lower surface of the leaves is
infested with all life stages of whiteflies.
• Both the nymphs and adults of whitefly feed on phloem cell sap and causes chlorotic
spots. The leaves dry-up prematurely and plant growth is affected. Nymphs also
secrete a sticky substance known as honeydew, which covers leaf surfaces and flowers
on which the sooty growth takes place under humid weather conditions.

MANAGEMENT STRATEGIES
Since greenhouse conditions allow rapid development of pest
populations, successful control of insect pests on greenhouse
vegetables and ornamentals depends on several factors
The IPM programme for protected cultivation can be described as a
pyramid constructed having three key components namely, Avoidance
of problem; Sampling and early detection; and Curative measures.

1. AVOIDANCE
1.1 Use of Physical Barriers
1.1.1 Use of Insect-proof screens
Pests such as thrips, aphids, leafminers and
whiteflies, but also some less common pests such as
fruit borers. Screening vents and doorways can
greatly limit the movement of insect pests into the
greenhouse. However, selection of proper screen
size mesh and assuring adequate airflow are more
important.
Table 2. Screen mesh sizes needed to exclude
major greenhouse pest species
Insect-Pest Hole size (micron)
Mesh (Number of
threads per linear inch)
Leafminer (L. trifoli) 610 34
Cotton whitefly (B. tabaci) 462 42
Aphid (M. persicae) 340 52
Greenhouse whitefly
(T. vaporariorum)
290 58
Thrips (Thrips spp.) 192 76

1.1.2 Provision of double door
Limited access to screened areas is beneficial
since insects may come in the protected
structure on clothing or be swept in with the
wind. Building a screened foyer to create a
double-door entry partially solve the problem
of wind-carried insects
1.1.3 Ultra-violet radiation absorbing sheets
• It was found that populations of aphid (A. gossypii), greenhouse
whitefly (T. vaporariorum), thrips (Frankliniella occidentales and
Scirtothrips dorsalis) and leafminer (Liriomyza sp.) were lower on
tomatoes grown in a plastic-house made of polyethylene treated to
exclude UV wavelengths than on crops grown in an ordinary
plastic house.
• The number of whiteflies, aphids and thrips trapped on sticky
yellow cards under a UV-absorbing film were 10 - 100 times lower
than the number trapped under regular films. The use of UV-A
films also helped in reducing the number of insecticide
applications by 50-80% for the management of Spodoptera
lituralis.

1.2 Sanitation and Cultural Practices
1.2.1 Pre-season cleanup
It has been observed that insects can enter the protected
structure in following three ways:
 Introduction of infested seedlings/ planting material
 Infestation from other plants within the protected structure
 Infestation from host plants outside but near the protected
structures
1.2.2 Inspection upon arrival
1.2.3 Balanced use of fertilizer
1.2.4 Pinching and Pruning
Pinching-off damaged plant parts, flowers, and
spotted leaves (and those with insect larvae or egg
deposits) can be a very effective way of reducing the
spread of pests in the greenhouse
Pruning lower leaves after harvesting lower fruit
clusters is helpful measure in removing large
numbers of developing leafminers and whiteflies

2.5 Plant Quarantine
2.6 Trap crop/Indicator plants
Planting border rows of Portulaca oleracea in rose can be
used as a trap crop for tobacco caterpillar under protected
environment.
2. EARLY DETECTION
Scouting and early detection are critical to manage the insect
infestation successfully. Monitoring or scouting is the regular,
systematic inspection of the plants and exteriors to identify and
assess pest problems. It includes inspection of foliage and
flowers; and the use of insect traps.

2.1 Scouting
Look at the older leaves, the young, tender
leaves, and the flush growth. When the crop is
young, it is important to check all the leaves on the
plant. Because a majority of arthropod pests
associated prefer the underside of a leaf, it is
important to turn the leaves over to check for
pests.
Scout the crop on a regular basis and at least 1-2%
of the total plants should be inspected at weekly
interval.
2.2 Monitoring
It is a relative method of insect population estimation where no
direct observations on the plants for the presence of insect-pests
are needed
However, the pest population is estimated with the help of
attractant traps. For whiteflies, aphids, thrips and leafminer
adults, yellow sticky cards (4″x12″ or 8″x12″) are an excellent
supplement to pest observation in the protected environment.
Additionally, for thrips blue coloured sticky traps can also be
used. The traps are placed in a grid pattern and 1-2 yellow
sticky cards per 100 square meter of floor area are used
Apart from this, sex pheromone baited traps can also be used for detecting moths of tobacco caterpillar and tomato fruit
borer.

Table 3. Monitoring and scouting technique for pests under protected environment
Aphids Leaf-
miners
Yellow
Mites
Spider
Mites
Thrips White-
flies
Caterpillars
Scouting:
Inspect underside
of leaf
X X X X X X
Inspect upper surface
for stippling/ small
white spots
X X
Inspect leaves for mines
within tissue
X
Inspect new growth or
terminal for feeding
X X X
Tap flowers over white
surface & look for
movement
X X X
Press lower leaf surface
on white card and look
for spots on cards
X X
Observe for:
Honeydew or
sooty mold
X
Small black spots
on leaves (fecal
drops)
X
Holes/
skeletonized spot
in/ on leaves
X
Frass on leaves X
Small black spots
on leaves (faecal
drops)
X
Chlorotic (yellow)
spots on upper
leaf surface
X X X
Casted-off skins
on leaf
X

Curling of leaves X X
Distortion of new growth X X X
Buds fail to open or
uneven opening of flowers
X
Webbing on leaves/
flowers
X
Monitoring
Yellow sticky card at top
of plant canopy
X X X X
Blue sticky card at top of
plant canopy
X
Pheromone traps X

3. CURATIVE MEASURES
3.1 Biological Control
Practically every crop pest has its natural
enemies in the form of parasitoids or
predators.
Use of specific predators and parasitoids in
greenhouse ecosystem to manage pests
forms the basics of biological control
Table 4. Registered natural enemies for pest management in
protected cultivation in Europe and United States
Target pest Biocontrol agent Scentific name
Whiteflies Parasitic wasps Encarsia Formosa
Serpentine leaf miner Leafminer parasitoid Dacnusca sibiriica
Diglyphus isaea
Spider mites Predatory mites Amblyseius californicus
Phytoseiulus longipes
Phytoseiulus persimilis
Thrips Predatory mites Amblyseius cucumeris
Amblyseius mckenziei
Various soft-bodied
insects and eggs
Lady beetles Hippodamia convergens
Cryptolaemus montrouzeri
Various soft-bodied
insects and eggs
Green lacewings Chrysoperla carnea

However, under Indian conditions this technique though is having potential
but have following limitations
 Temperature extremes and the effect of chemical pesticides affecting the
capabilities of natural enemies.
 Low tolerance of pest damage amongst consumers especially in
ornamentals
 Lack of a system for supplying natural enemies of good quality

3.2 Chemical Control
The insecticides are curative
in action and are one of the
important tools to check the
flaring pest populations.
Insecticides belonging to
different groups namely,
botanicals pesticides,
microbial pesticides, Insect
Growth Regulators (IGR),
synthetic chemical pesticides
etc. are in use.

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